When creating devices which allow to reproduce musical pieces on stringed instruments without human input, a problem arises for pressing strings to respective frets.
One possible solution described in the U.S. Pat. No. 6,723,904 (publ. on Apr. 20, 2004) proposes a controlled moving carriage which disposing above a certain fret on the finger-board ensures a simultaneous press of all strings of the instrument to that fret, including the string which would sound. Such a solution has, besides its complexity due to the necessity for moving quickly the pressing carriage, a very limited use, since, when using that device, it is possible to play only those chords in which all strings are pressed to the same fret.
Solution for this problem are known where the strings' press is performed using solenoids mounted above or under the strings (see, for example, the Japan Patent Applications 2009-031494, publ. on Feb. 12, 2009, and 2010-266832, publ. on Nov. 25, 2010). In all those and other similar solutions, the solenoids ensure a stop of strings by means of intermediate mechanisms which are complex enough and require special means for excluding a knock arisen at a moment of actuating the solenoid.